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238 



THE AUKIFEKOUS GEAYELS OF THE SIEEEA NEVADA. 



posits are mineralized with sulphuret of iron. This substance may form the 

 whole mass of the fragment, but is sometimes deposited in crystalline plates 

 in the fissures, or as a crust on the exterior. 



The following particulars in regard to the occurrence of fossil wood and 

 leaves in the region explored by Mr. Goodyear are extracted from his notes. 



At the Reed Mine, near Dead wood, at the elevation of about 3,600 feet 

 the gray cement, as well as the so-called " chocolate," — a sort of indurated 

 volcanic mud, — often contains more or less apparently half carbonized wood. 

 And, besides these fragments of wood, numerous trees have been found here, 

 still in their upright position, with their roots upon and ramifying into the 

 bed-rock, and their stems and tops projecting through the " chocolate " and 

 up into the "gray cement." The trees thus found standing are not very 

 large, none of them beina; much over a foot in diameter. All had their roots 

 on and in the bed-rock, and none in the "chocolate." This last-named ma- 

 terial contained also occasional impressions of leaves, very perfectly pre- 

 served. At Weske's Claim, near Michigan Bluff, where fragments of trees 

 and wood are common in the cement, some trees are also said to have been 

 found in an upright position, with their roots in place on the bed-rock. In 

 the Basin Channel, at the Devil's Basin, Mr. Goodyear saw, at one locality, 

 a fossil tree standing vertically in the a gray cement." 



Fossil wood is of frequent occurrence in the finer material of volcanic 

 origin which overlies the gravel, in the claims along the western side of the 

 ridge near Deadwood. At Kentucky Flat, also, there is considerable wood 

 in the volcanic ash. In the Oldfield and adjacent claims at Negro Hill, near 

 Placerville, the whole mass of the u black lava " contains frequent casts of 

 sticks and broken bits of wood, and sometimes, also, delicately preserved im- 



r 



pressions of leaves, which latter are generally more or less bent or twisted. 



The village of Fairplay is just south of Perry's Creek, a tributary of the 

 Middle Fork of the Cosumnes River. There is a large amount of volcanic 

 gravel in this region, and at Fairplay considerable mining has been done. 

 It is said that in the volcanic gravel on Fairplay Hill there was once found 

 a * natural shaft " three or four feet in diameter, with its sides covered with 

 a substance resembling soot. This was probably the cast of an erect fossil 



tree. 



At the Roanoke Mine, near Georgetown, large quantities of wood were 

 found in the cement ; and it is said that it was a common tiling to observe 

 here, along the sides of the channel, at about the level of the top of the 



